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  2. Vertical and horizontal - Wikipedia

    en.wikipedia.org/wiki/Vertical_and_horizontal

    Any plane going through P, normal to the horizontal plane is a vertical plane at P. Through any point P, there is one and only one horizontal plane but a multiplicity of vertical planes. This is a new feature that emerges in three dimensions. The symmetry that exists in the two-dimensional case no longer holds.

  3. Four prism dioptre reflex test - Wikipedia

    en.wikipedia.org/wiki/Four_prism_dioptre_reflex_test

    assess alignment of both eyes. The Four Prism Dioptre Reflex Test (also known as the 4 PRT, or 4 Prism Dioptre Base-out Test) is an objective, non-dissociative test used to prove the alignment of both eyes (i.e. the presence of binocular single vision) by assessing motor fusion. [1] Through the use of a 4 dioptre base out prism, diplopia is ...

  4. Vertical exaggeration - Wikipedia

    en.wikipedia.org/wiki/Vertical_exaggeration

    Vertical exaggeration is given as a number; for example 5× means vertical measurements appear 5 times greater than horizontal measurements. A value of 1× indicates that horizontal and vertical scales are identical, and is regarded as having "no vertical exaggeration." Vertical exaggerations less than 1 are not common, but would indicate a ...

  5. Fixation disparity - Wikipedia

    en.wikipedia.org/wiki/Fixation_disparity

    Eye glasses with an included prism power is the optical method to reduce a fixation disparity. Different procedures have been proposed to determine the required amount of prism for the individual. Based on prism-FD curves (Fig. 3b), one can find the aligning prism sP 0 that nullifies the naturally prevailing fixation disparity sFD 0. This test ...

  6. Pentagonal prism - Wikipedia

    en.wikipedia.org/wiki/Pentagonal_prism

    As a semiregular (or uniform) polyhedron. If faces are all regular, the pentagonal prism is a semiregular polyhedron, more generally, a uniform polyhedron, and the third in an infinite set of prisms formed by square sides and two regular polygon caps. It can be seen as a truncated pentagonal hosohedron, represented by Schläfli symbol t {2,5}.

  7. Schmidt–Pechan prism - Wikipedia

    en.wikipedia.org/wiki/Schmidt–Pechan_prism

    A Schmidt–Pechan prism is a type of optical prism used to rotate an image by 180°. These prisms are commonly used in binoculars as an image erecting system. The Schmidt–Pechan prism makes use of a roof prism section (from the German: "Dachkante", lit. roof edge ). Binoculars designs using Schmidt–Pechan prisms can be constructed more ...

  8. Wedge prism - Wikipedia

    en.wikipedia.org/wiki/Wedge_prism

    Wedge prism. The wedge prism is a prism with a shallow angle between its input and output surfaces. This angle is usually 3 degrees or less. Refraction at the surfaces causes the prism to deflect light by a fixed angle. When viewing a scene through such a prism, objects will appear to be offset by an amount that varies with their distance from ...

  9. Level (optical instrument) - Wikipedia

    en.wikipedia.org/wiki/Level_(optical_instrument)

    Level (optical instrument) A level is an optical instrument used to establish or verify points in the same horizontal plane in a process known as levelling. It is used in conjunction with a levelling staff to establish the relative height or levels (the vertical separation) of objects or marks. It is widely used in surveying and construction to ...